Hydrogen Bonding of Cholesterol in the Lipidic Cubic Phase

Abstract

The addition of cholesterol to the monoolein-based lipidic cubic phase (LCP) has been instrumental in obtaining high-resolution crystal structures of several G protein-coupled receptors. Here, we report the use of high resolution magic angle spinning NMR spectroscopy to record and assign the isotropic 13C chemical shifts of cholesterol in lipidic lamellar and cubic phases at different hydration levels with monoolein and chain deuterated DMPC as host lipids. The hydrogen bonding patterns of cholesterol in these phases were determined from the NMR data by quantum chemical calculations. The results are consistent with the normal orientation of cholesterol in lipid bilayers and with the cholesterol hydroxyl group located at the hydrophobic/hydrophilic interface. The 13C chemical shifts of cholesterol are mostly affected by the host lipid identity with little or no dependency on the hydration (20% vs. 40%) or the phase identity (lamellar vs. LCP). In chain deuterated DMPC bilayers, the hydroxyl group of cholesterol forms most of hydrogen bonds with water, while in monoolein bilayers it predominately interacts with monoolein. Such differences in the hydrogen-bonding network of cholesterol may have implications for the design of experiments in monoolein-based LCP.

Two Classes of Cholesterol Binding Sites for the β 2 AR Revealed by Thermostability and NMR

“…The chemical shifts and assignments of the sterol methyl peaks in LCPs, and in chloroform solution for comparison, are given in Table 1. Detailed comparisons of the chemical shifts of cholesterol in CDCl 3 solution, lipid bilayers and in LCP were previously reported (33,34,38). Although the addition of proteins or peptides to the LCP can potentially affect diffusion rates of lipids (18) and phase transitions, b 2 AR did not significantly alter any of the cholesterol 13 C chemical shifts in our samples, indicating that the protein did not have a particular effect on the cholesterol-MO-water hydrogen-bonding network at the lipid-water interface.…”

Structural insights into the cubic–hexagonal phase transition kinetics of monoolein modulated by sucrose solutions

“…34 Consequently, lipid-protein crystals offer a fruitful arena for examining the effects of membrane composition on proteins. 35–37 There are also promising efforts to use these crystals to probe femto-second time scale behavior of proteins. 38 …”

Cation ion specifically induces a conformational change in trans-dehydroandrosterone – A solid-state NMR study

“…For example, it has been utilized to determine the average orientation and dynamics of ergosterol [16][17][18] and cholesterol [19] in model membranes and steroid/lipid interaction [20][21][22]. Cross-polarization [23]/magic angle spinning [24] (CP/MAS) 13 C NMR solid-state spectroscopy techniques provide high-resolution spectra comparable to those observed in the solution phase, such that conformational information can be directly accessed.…”